Development and Validation of New Dual-doppler Analysis Techniques with Emphasis on the Vertical Velocity Problem

Abstract

Abstract : Our longterm goal is to develop new dual-Doppler analysis techniques with an emphasis on improving estimates of the vertical velocity field. Our main objective is to use a dynamical constraint (vertical vorticity equation) to improve dual- Doppler analyses of the vertical velocity field over those obtained with traditional methods. This work involves the development and testing of three new techniques (based on variational methods) to analyze the wind and vertical velocity field from dual-Doppler radar data. These methods all rely on the Boussinesq form of the vertical vorticity equation imposed as a weak or strong constraint, with and without the anelastic mass conservation equation (Mewes and Shapiro 1999). In each method the relevant Euler-Lagrange equations are solved numerically (they are either elliptic equations or can be made elliptic by applying a small amount of spatial smoothing). These methods are designed to contend with the irregular lower/upper boundaries of the data region--in essence, the methods seek to derive the optimal boundary condition for the vertical velocity field on these irregular boundaries. These techniques are being tested on simulated radar data sampled from high resolution runs of a numerical weather prediction model, the Advanced Regional Prediction System (ARPS).